[PATCH v3 8/9] leon3: check cpu_id in the tiny bootloader

Clément Chigot posted 9 patches 10 months ago
Maintainers: "Clément Chigot" <chigot@adacore.com>, Frederic Konrad <konrad.frederic@yahoo.fr>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, Artyom Tarasenko <atar4qemu@gmail.com>
[PATCH v3 8/9] leon3: check cpu_id in the tiny bootloader
Posted by Clément Chigot 10 months ago
Now that SMP is possible, the asr17 must be checked in the little boot code
or the secondary CPU will reinitialize the Timer and the Uart.

Co-developed-by: Frederic Konrad <konrad.frederic@yahoo.fr>
Signed-off-by: Clément Chigot <chigot@adacore.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/sparc/leon3.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/hw/sparc/leon3.c b/hw/sparc/leon3.c
index 252aff72cd..798dba1e5a 100644
--- a/hw/sparc/leon3.c
+++ b/hw/sparc/leon3.c
@@ -99,13 +99,27 @@ static uint32_t *gen_store_u32(uint32_t *code, hwaddr addr, uint32_t val)
 
 /*
  * When loading a kernel in RAM the machine is expected to be in a different
- * state (eg: initialized by the bootloader). This little code reproduces
- * this behavior.
+ * state (eg: initialized by the bootloader).  This little code reproduces
+ * this behavior.  Also this code can be executed by the secondary cpus as
+ * well since it looks at the %asr17 register before doing any
+ * initialization, it allows to use the same reset address for all the
+ * cpus.
  */
 static void write_bootloader(CPUSPARCState *env, uint8_t *base,
                              hwaddr kernel_addr)
 {
     uint32_t *p = (uint32_t *) base;
+    uint32_t *sec_cpu_branch_p = NULL;
+
+    /* If we are running on a secondary CPU, jump directly to the kernel.  */
+
+    stl_p(p++, 0x85444000); /* rd %asr17, %g2      */
+    stl_p(p++, 0x8530a01c); /* srl  %g2, 0x1c, %g2 */
+    stl_p(p++, 0x80908000); /* tst  %g2            */
+    /* Filled below.  */
+    sec_cpu_branch_p = p;
+    stl_p(p++, 0x0BADC0DE); /* bne xxx             */
+    stl_p(p++, 0x01000000); /* nop */
 
     /* Initialize the UARTs                                        */
     /* *UART_CONTROL = UART_RECEIVE_ENABLE | UART_TRANSMIT_ENABLE; */
@@ -119,6 +133,10 @@ static void write_bootloader(CPUSPARCState *env, uint8_t *base,
     /* *GPTIMER0_CONFIG = GPTIMER_ENABLE | GPTIMER_RESTART;        */
     p = gen_store_u32(p, 0x80000318, 3);
 
+    /* Now, the relative branch above can be computed.  */
+    stl_p(sec_cpu_branch_p, 0x12800000
+          + (p - sec_cpu_branch_p));
+
     /* JUMP to the entry point                                     */
     stl_p(p++, 0x82100000); /* mov %g0, %g1 */
     stl_p(p++, 0x03000000 + extract32(kernel_addr, 10, 22));
-- 
2.25.1